Bushing type circuit interrupter



(i. Haus/v fzs Sepi- 1, 1953 MAsATosHl KUWAYAMA 2,650,972

BUSHING TYPE CIRCUIT` INTERRUPTER Filed March 14, 1951 2 Sl'leecs-Sheefll INVENTOR. 745A falsi/f gwn/HMH BY l X4/vm,

Patented Sept. 1, 1953 UNITED STATES PATENT OFFICE Masatoshi Kuwayama,Taga, Japan, assignor to Hitachi Limited, Tokyo, Japan Application March14, 1951, Serial No. 215,504 In Japan April 28, 1950 3 Claims.

This invention relates to an improvement in bushing type circuitbreakers, and more particularly to a special construction andarrangement of the arc extinguishing cylinder of the circuit interruptercomprising a plurality of circuit interrupting points arranged incataract stages, and its object is to provide an electric circuitinterrupter having positive and quick arc extinguishing ability inopening the circuit.

With the above objects in view, the invention consists of novelconstruction and arrangement of parts hereinafter fully described andclaimed.

In the accompanying drawing forming a part of this specication:

Fig. l is a sectional elevation of a bushing type circuit interrupter asan embodiment of this invention showing the parts at the circuit opencondition,

Fig. 2 is a sectional elevation of main parts of the bushing typecircuit interrupter shown in Fig. l at the closed position, and

Fig. 3 is a sectional elevation similar to Fig. 2 at an intermediatestate of circuit opening operation.

Referring to the drawing, I represents an insulator bushing forming anoil tank which is xed on a closed metallic casing 2 supported on postinsulators (not shown) to be insulated from the ground. 3 represents alever xed to an actuating shaft 4 oi the circuit interrupter, whichpasses through the wall of the metallic casing 2 with oil tight packingand is arranged to be operated from the outside of the casing. 5represents a link pivoted intermediate of its ends to the end of thelever 3 and at its one end engaging a guide groove yg provided in thecasing 2 and at the other end connected to a cross head 6. I representsa movable contact and 8 designates a push rod, these members being fixedto the cross head 6 and projected upward. 9 represents a guide memberfor the members 'I and 8; and I0 represents the lowest fixed contactserving also as a guide.

I I represents an upper metallic casing xed on top of the bushing I, andI2 represents the oil level. I3 represents a metallic terminal memberwhich is fixed to the upper casing I I and has an arc extinguishingcylinder I4 xed to and suspended from its lower end. The inside of thearc extinguishing cylinder I4 is divided into at least three separateoil chambers A, B and C by means of the partitions I5 and I6. In thelowest oil chamber C, there is formed an arc suppressing chamber I'Iwhich has zig-zag inside surface and .oil outlet holes I8 and oil inletholes I9. 20 represents an intermediate arc extinguishing xed contactsecured to the partition wall Iii. 2l represents an upper stationaryContact fixed to the upper wall of the oil chamber A, and 23 representsan intermediate stationary contact xed to the lower Wall of the chamberA beneath the contact 2| and an arc suppressing chamber Z2 is formedbetween the contacts ZI and 23 enclosing the arc passage of thesecontacts. 2:. is an intermediate movable contact which passes throughthe partition walls I5 and Iii to cooperate with the contact 23 and isheld normally in an open lowered position by a spring 26 acting on itscollar 25. 21 represents an insulator or insulated rod xed to the lowerend of the intermediate movable Contact 24 and extended into the loweroil chamber C, and the rod 2 is covered by an insulator cylinder 23.

Oil chambers A, B, and C are communicated through holes h. In the upperoil chamber A, an arc inducing electrode 29 is projected adjacent to thearc suppressing chamber 22 and a gas blowoi valve 3@ is fitted to thetop wall of the oil chamber A. 3| designates a cylinder of an oil jetdevice provided for the top Wall of the oil chamber A above the pressuregenerating contact 2 I. 32 is a piston slidably fitted in the cylinder3l and acted upon by a spring. 33 represents a piston rod xed to thepiston 32 and projecting through the pressure generating contact 2 I.

The arc extinguishing cylinder It is entirely surrounded by a protectiveinsulator cylinder 3d which is secured to a part of the upper metalcasing I I by means of metal pieces 35 and suspended therefrom into thebushing I. The cylinders I4 and 34 have holes 33 and 3l in their bottomwalls for passing therethrough the movable contact 'l and the push rod 8respectively. G1 represents an insulating liquid between the bottom ofthe arc extinguishing cylinder I4 and the lower Xed contact I0.

Fig. 1 illustrates a condition when the circuit breaker is open. Inorder to close the circuit breaker, the operating shaft 4 should beturned clockwise, thereby turning the lever 3, then the link 5 isshifted to raise the cross head 6 vertically. By the vertical upwardmovement of the cross head 6, the movable contact 'I is moved into thearc suppressing chamber I'I through the holes 35 and is made to contactwith the intermediate stationary electrode 2i), while the push rod 8enters into the insulator cylinder 28 through the holes 3i' and engagesthe lower end of the insulator rod 2l and moves the latter upwards sothat the top end of the intermediate movable contact 24 is forced intothe pressure generating contact 2l. Meanwhile the piston rod 33 ispushed up by the top end portion of the movable contact 261 to move thepiston 32 upwards and the oil is sucked into the cylinder. Such closedcondition of the circuit breaker is shown in Fig. 2, wherein theelectric path is established from the upper metal casing and themetallic terminal piece i3 through the upper stationary contact 2 l, theintermediate movable contact 24, the intermediate stationary contact 23,the metallic partition walls l5 and i6, the intermediate stationarycontact 2t, the movable contact l, the lower xed'contact lll and theguide metal piece il leading to the lower metal casing 2.

The opening of the circuit breaker is eiected by turning the operatingshaft 4 to the counterclockwise direction, thereby quickly forcing downthe movable contact 'I and the push rod 8 by the aid of snap spring andthe like means (not shown). Upon the downward movement of the members 'land B, the pressure generating movable contact 24 is moved downwards bythe action of the accelerating spring 25 following the downward movementof the push rod 8 and opens the contact with the upper stationarycontact 2| and also the movable electrode l opens the contact with thearc extinguishing contact 20, thus eiecting so-called seriesinterruption.

Fig. 3 illustrates an intermediate condition of the circuit openingoperation of the present circuit breaker showing the arcsdeveloped'between the cooperating contacts when they are opened. Atfirst, an arc is generated between the pressure generating contacts -2|and r213 producing the pressure by the pressure generating arc, but suchare, in case of cutting off a vsmall current, is shifted toward the arcguiding electrode 29 located outside of and adjacent to the arcsuppressing chamber 22 by the oil jet caused by the downward movement ofthe piston 32 and the length of the arc is increased as shown by a2 andthe arc decomposes a suincient amount of oil, thereby raising the vapourpressure and forces the fresh oil inthe chamber B into the arcsuppressing chamber l'i which encloses the lower contact points andthearc generated between the contacts 20 and "l is subjected to the oilcurrent and blown laterally out of the passages I8 inducing cooling oilto iiow through the passages I9 and the arc extinguishing action isaccelerated. The arc extinguishing oil current, as it consists mainly ofa fresh oil in the chamber B,has a high ability of arc extinguishing.Meanwhile the arc generated between the upper Contact points issubjected to the powerful arc extinguishing action so that the arc maybe extinguished before the top end of the movable contact l is pulledout of the lower part of the arc suppressing chamber il and the circuitis completely interrupted.

Thus after the arc has been extinguished, the top ends of the movablecontact 'i and the push rod 8 respectively are brought to the lowestposition through the oil layer G1, the bottom of the protectiveinsulator cylinder I4 and the oil layer G2, and are rested at thecircuit open condition as shown in Fig. 1. The gases remaining in thearc extinguishing chamber after the completion of circuit openingoperation are exhausted upwards through the blow-off valve 30 -providedin the top wall of the chamber A and the are suppressing chamber is lledwith fresh oil.

According to the present invention, the internal members in the arcextinguishing cylinder 4 can be made comparatively simple and the arcextinguishing cylinder can easily be inspected by lifting it up out ofthe protective insulator cylinder.

Owing to the arrangement of the movable pressure generating and arcextinguishing contacts to move in the same direction relative to thecooperating stationary contacts respectively, the time of opening thesecontact points can be adjusted by adjusting the movable contacts and theaction of oil current caused by the arcs generated at these circuitinterrupting points can be selected to be most effective forextinguishing the arc.

The further advantage of this invention is to remarkably improve thecircuit interrupting properties of circuit breakers by moving themovable contact and the push rod downwards through the insulating oillayers G1 and G2 resulting in so-called oil interrupting eiect.

Having thus described my invention, what I claim as new and desire tosecure by Letters Patent of the United States is:

1. In a bushing type electric circuit interrupter, in combination aninsulator bushing, an are extinguishing cylinder suspended in saidinsulator bushing, said kare extinguishing cylinder being divided intoat least three successive superimposed compartments communicatingthrough small holes, a pressure generating stationary contact fixed onthe top wall of the upper compartment thereof, a second stationarycontact fixed to the bottom wall of said upper compartment, a pressuregenerating movable contact member passing through said second contactcooperable with said pressure generating stationary contact, saidmovable contact being normally biased by a spring into a downwardposition out of engagement with said pressure generating stationarycontact, an arc extinguishing stationary contact xed to the top wall oithe lower'compartment on a vertical line spacedfrom the vertical axis ofthe contact member, a second movable contact member cooperable with saidarc extinguishing stationary contact, an Yinsulated push rod foractuating said pressure generating movable contact member, a cross headto which the lower ends of said second contactmember and said push rodare xed uprightly and with a predetermined distance betweenthem, a guidemember xed to the bottom portion of said bushing and having a fixedguide contact and aguide for said second contact member and the push rodrespectively, and means for operating the cross head in vertical-up anddown directions.

2. A bushing type electric circuit interruptor, comprising an insulatorbushing, an arc-extinguishing cylinder suspended in the `insulatorbushing, said bushing and said cylinder vcontaining insulating liquid,said arc extinguishing. cylinder being divided into at least-threeconsecutive chambers by partitions and communicating together throughholes in the partitions, a :pressure generating stationarycontact xed tothe top wall of the uppermost chamber, a combination stationary lContactand guide xed to the partition of the bottom of the uppermost chamber, apressure generating-movable contact member for engagement with saidstationary contact passed slidably through` said contact and guide andnormally biased by a spring to a position out of contact with saidstationary contact, an arc extinguishing chamber provided in theuppermost chamber arranged to enclose the pressure generatingstaticnarycontact, an oil jet/device having a piston acted on by aspring mounted on said cylinder, said piston having a piston rod passingthrough the pressure generating stationary contact to inject theinsulating liquid into the arc extinguishing chamber, an arcextinguishing contact mounted Within the lowermost chamber of said arcextinguishing cylinder, a movable contact member cooperable with saidarc extinguishing contact, a guide contact supported below said cylinderin alignment with said arc extinguishing contact, an arc suppressingchamber Within said lowermost chamber surrounding the arc path of thelast mentioned cooperating contacts, a push rod arranged to force upsaid pressure generating movable contact member, a guide frame xed tothe bottom end of said bushing and supporting said guide contact andguide for said movable contact member and said push rod respectively thelower ends of which are secured to a cross head, a moving link mechanismfor operating said cross head in vertical up and down directions, and aprotective insulator cylinder Within said bushing and surrounding saidarc extinguishing cylinder.

3. In a bushing type electric circuit interrupter having an uppermetallic terminal member, an arc extinguishing cylinder secured to andsuspended from the terminal member, spaced partitions within saidcylinder dividing it into three superimposed chambers, said partitionshaving holes providing communication between said chambers, the middleone of said chambers being a reservoir for fresh insulating liquid forextinguishing an arc, a pair of stationary contacts supported within thetop and bottom chambers of said cylinder, arc suppressing chamberswithin the top and bottom chambers for the respective contacts andenclosing their are passages, an intermediate movable contact rodsupported by said partitions to be engageable with the contacts of thetop chamber when raised and having a downwardly extended rod ofinsulation material, a spring operating between a iixed part of saidcontact rod and one of said partitions holding said contact rod out ofengagement with the contact of the top chamber, an oil jet cylinder xedto the top of said arc extinguishing cylinder above the contact of thetop chamber, a piston slidably positioned within said jet cylinder andhaving a portion extended into the contact of said top chamber to beraised by said contact rod when lifted into engagement with the contactof the top chamber, a blow-oir valve for residual gases mounted incommunication with the top chamber or" said arc extinguishing cylinder,an oil filled bushing enclosing said arc extinguishing cylinder, aprotective insulator cylinder extended into said bushing and enclosingsaid arc extinguishing cylinder and being apertured to receive oil fromsaid bushing, an arc extinguishing movable contact rod for engagementwith the contact of the bottom chamber, a push rod for raising saidintermediate movable contact rod into engagement with the contact of thetop chamber, a stationary contact for guiding the arc extinguishingmovable contact rod, a guide member for said push rod, a cross headsecured to the lower ends of said arc extinguishing contact rod and saidpush rod, means for raising said cross head vertically to raise andlower said arc extinguishing contact rod and said push rod so that thetop end portions of said arc extinguishing rod and said push rod will becontacted by the fresh liquid in the bushing in the fully loweredposition of said cross head, said means comprising a link pivoted at oneend on the cross head and held at its other end to move along a xedslot, a lever secured at one end to an operating shaft and pivotallysecured at its other end to said link, and a metallic casing having aclosed bottom secured to the bottom of said bushing and insulated fromthe ground and enclosing the cross head, link and lever, said metalliccasing being filled with an insulating liquid.

MASATOSHI KUWAYAMA.

References Cited in the le of this patent UNITED STATES PATENTS NumberName Date 2,412,858 Baker et al Dec. 1'7, 1946 2,422,569 Leeds June 17,1947 2,470,611 Friedrich May 17, 1949 2,530,952 Fry Nov. 21, 1950

